Energy-efficient multi-hop communication schemes for wireless networks

ABSTRACT

A method in a node is disclosed. The method comprises determining ( 1304 ) a first route from a first source node ( 505  A) to a destination ( 510 ), the first route comprising one or more relay nodes ( 515, 615 ). The method comprises determining ( 1308 ) an energy-harvesting routing metric, the energy-harvesting routing metric for use in determining a second route from a second source node ( 505 B) to the destination ( 510 ). The method comprises determining ( 1312 ) the second route from the second source node ( 505 B) to the destination ( 510 ), the determined second route comprising one or more relay nodes ( 515, 615 ) selected to maximize the determined energy-harvesting routing metric.

PRIORITY

This nonprovisional application is a U.S. National Stage Filing under 35U.S.C. § 371 of International Patent Application Serial No.PCT/SE2016/052139 filed Apr. 14, 2016, and entitled “Energy-EfficientMulti-hop Communication Schemes For Wireless Networks” which claimspriority to U.S. Provisional Patent Application No. 62/148,050 filedApr. 15, 2015, both of which are hereby incorporated by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates, in general, to wireless communicationsand, more particularly, to energy-efficient multi-hop communicationschemes for wireless networks.

BACKGROUND

To cope with the exponential growth in wireless data traffic, it isanticipated that substantially denser deployments of base stations orwireless access nodes will be required in the future. The feasibility ofa very dense deployment of wireless access nodes is predicated on theexistence of a backhaul network that can provide high-data-ratetransport for each individual access node in the network. From the pointof view of maximizing capacity, optical-fiber-based backhaul solutionsare probably the most desirable and are most suitable for newconstructions. However, in existing buildings and infrastructure, thecost of installing new fibers to every access node in a very densenetwork can be prohibitive.

An alternative is the wireless self-backhaul solution, where the sameaccess spectrum is used to provide transport. With self-backhauling, anaccess node serves not only its own assigned user equipment (UEs) in itsvicinity, but also its neighboring access nodes as a relaying node inorder to transfer data towards and/or from an information aggregationnode (AgN) in the network. A group of self-backhauling access nodes canform a multi-hop mesh network. Access nodes cooperatively transfer eachother's traffic to and from the aggregation node.

Due to the broadcast nature of the wireless medium, interference becomesa main limiting factor on network throughput for a wireless multi-hopbackhaul network. Interference-aware routing has been proposed and shownto offer a significant throughput gain over shortest-path routing. Ajoint routing and resource allocation for wireless self-backhaulnetworks was presented in “Joint Routing and Resource Allocation forWireless Self-Backhaul in an Indoor Ultra-Dense Network,” Proc. IEEEInt. Symp. Personal, Indoor and Mobile Radio Comm., pp. 3083-3088,London, U K, 2013 (“Joint Routing and Resource Allocation”). Because itis assumed that each relay decodes its desired message by treating othersignals as noise, an interference-aware routing algorithm aims to avoidinter-path interference. It was shown in “Joint Routing and ResourceAllocation,” however, that this approach incurs significant limitationon network throughput at high load (i.e., the number of sources islarge). This result is expected since it is nearly impossible to avoidall inter-path interference at high load. Furthermore, because thetransmission rate on every route is determined by the minimum of alllink-capacities on the route, one strong interference on a path candrastically degrade the end-to-end performance. Thus, there is a needfor a more advanced coding scheme that can efficiently manage stronginterference instead of simply treating it as noise.

SUMMARY

To address the foregoing problems with existing approaches, disclosed isa method in a node. The method comprises determining a first route froma first source node to a destination, the first route comprising one ormore relay nodes. The method comprises determining an energy-harvestingrouting metric, the energy-harvesting routing metric for use indetermining a second route from a second source node to the destination.The method comprises determining the second route from the second sourcenode to the destination, the determined second route comprising one ormore relay nodes selected to maximize the determined energy-harvestingrouting metric.

In certain embodiments, the first route and the second route maycomprise different numbers of relay nodes. The determined first routemay comprise a route having a shortest number of hops between the firstsource node and the destination. Maximizing the energy-harvestingrouting metric may comprise maximizing an achievable rate betweenconsecutive relay nodes. The energy-harvesting routing metric maycomprise a multiple input multiple output (MIMO) channel capacity. Theenergy-harvesting routing metric may be a function of signal-to-noiseratios. The energy-harvesting metric may be determined to maximizeinterference between routes. The relay nodes may perform noisy networkcoding.

In certain embodiments, determining the second route from the secondsource node to the destination may comprise: determining one or morefirst candidate relay nodes, the first candidate relay nodes locatedwithin a communication range of the second source node; determiningwhich of the one or more first candidate relay nodes maximizes theenergy-harvesting routing metric, wherein the determination of which ofthe one or more first candidate relay nodes maximizes theenergy-harvesting routing metric is based on energy-harvesting routingmetrics of the first source node, the second source node, and a firstrelay node of the first route; and selecting a first candidate relaynode that maximizes the energy-harvesting routing metric as the firstrelay node of the second route. In certain embodiments, the method maycomprise determining one or more second candidate relay nodes, thesecond candidate relay nodes located within a communication range of theselected first relay node of the second route; determining which of theone or more second candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or moresecond candidate relay nodes maximizes the energy-harvesting routingmetric is based on energy-harvesting routing metrics of the first relaynode of the first route, the first relay node of the second route, and asecond relay node of the first route; and selecting a second candidaterelay node that maximizes the energy-harvesting routing metric as thesecond relay node of the second route.

In certain embodiments, the method may comprise optimizing thedetermined first route based on the determined second route, the secondroute comprising one or more relay nodes selected according to thedetermined energy-harvesting routing metric, wherein the optimized firstroute maximizes the energy-harvesting routing metric. In certainembodiments, optimizing the determined first route based on thedetermined second route may comprise: determining one or more thirdcandidate relay nodes, the third candidate relay nodes located within acommunication range of the first source node; determining which of theone or more third candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric is based on the energy-harvesting routing metric of the firstsource node, the second source node, and a first relay node of thesecond route; and selecting a third candidate relay node that maximizesthe energy-harvesting routing metric as a new first relay node of thefirst route. In certain embodiments, the method may comprise determiningone or more fourth candidate relay nodes, the fourth candidate relaynodes located within a communication range of the new first relay nodeof the first route; determining which of the one or more fourthcandidate relay nodes maximizes the energy-harvesting routing metric,wherein the determination of which of the one or more fourth candidaterelay nodes maximizes the energy-harvesting routing metric is based onthe energy-harvesting routing metric of the new first relay node of thefirst route, the first relay node of the second route, and the secondrelay node of the second route; and selecting a fourth candidate relaynode that maximizes the energy-harvesting routing metric as a new secondrelay node of the first route.

In certain embodiments, the method may comprise optimizing thedetermined second route based on the optimized first route, wherein theoptimized second route maximizes the energy-harvesting routing metric.In certain embodiments, the method may comprise continuing to optimizethe determined first and second routes until the energy-harvestingrouting metric for both the first and second routes exceeds a thresholdvalue.

In certain embodiments, the method may comprise: defining a plurality ofsubnetworks, the defined plurality of subnetworks comprising at least afirst subnetwork comprising the destination and the first and secondsource nodes and a second subnetwork comprising a second destination anda plurality of source nodes associated with the second destination, theplurality of source nodes including at least one additional source node;determining a first route for the second subnetwork from one of theplurality of source nodes associated with the second destination to thesecond destination, the first route for the second subnetwork comprisingone or more relay nodes; determining a second route for the secondsubnetwork from another of the plurality of source nodes associated withthe second destination to the second destination, the determined secondroute for the second subnetwork comprising one or more relay nodesselected to maximize the determined energy-harvesting routing metric;and optimizing the determined first route for the second subnetworkbased on the determined second route for the second subnetwork, thesecond route for the second subnetwork comprising one or more relaynodes selected according to the determined energy-harvesting routingmetric, wherein the optimized first route for the second subnetworkmaximizes the energy-harvesting routing metric. In certain embodiments,the first route for the second subnetwork may be determined usinginterference-aware routing.

Also disclosed is a node. The node comprises one or more processors. Theone or more processors are configured to determine a first route from afirst source node to a destination, the first route comprising one ormore relay nodes. The one or more processors are configured to determinean energy-harvesting routing metric, the energy-harvesting routingmetric for use in determining a second route from a second source nodeto the destination. The one or more processors are configured todetermine the second route from the second source node to thedestination, the determined second route comprising one or more relaynodes selected to maximize the determined energy-harvesting routingmetric.

Also disclosed is a computer program product. The computer programproduct comprises instructions stored on non-transient computer-readablemedia which, when executed by one or more processors, perform the actsof: determining a first route from a first source node to a destination,the first route comprising one or more relay nodes; determining anenergy-harvesting routing metric, the energy-harvesting routing metricfor use in determining a second route from a second source node to thedestination; and determining the second route from the second sourcenode to the destination, the determined second route comprising one ormore relay nodes selected to maximize the determined energy-harvestingrouting metric.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, certain embodiments mayadvantageously improve data throughput over the conventional(single-route) routing solution. As another example, in certainembodiments interfering signals received at a relay node are forwardedthrough QMF and treated as a useful signal at the destination node,which may advantageously result in better performance when the networkis dense and interference is high. As still another example, certainembodiments may provide for longer one-hop transmission, which mayadvantageously increase network throughput by decreasing the number ofrelay stages. As yet another example, certain embodiments mayadvantageously be more efficient in avoiding inter-network interferencethan interference-aware routing. Other advantages may be readilyapparent to one having skill in the art. Certain embodiments may havenone, some, or all of the recited advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed embodiments and theirfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication network, in accordance with certain embodiments;

FIG. 2 illustrates an example wireless mesh network including multiplesource nodes and one destination, in accordance with certainembodiments;

FIG. 3 illustrates an example of interference-aware routing;

FIG. 4 illustrates an example of energy-harvesting routing, inaccordance with certain embodiments;

FIG. 5 illustrates a first step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments;

FIG. 6 illustrates a second step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments;

FIG. 7 illustrates a third step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments;

FIG. 8 illustrates a fourth step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments;

FIG. 9 illustrates a performance comparison of energy-harvesting routingand interference-aware routing for three relay stages and 4 datasources, in accordance with certain embodiments;

FIG. 10 illustrates a performance comparison of energy-harvestingrouting and interference-aware routing for signal-to-noise ratio of 20dB, in accordance with certain embodiments;

FIGS. 11A and 11B illustrate two example use cases of energy-harvestingrouting, in accordance with certain embodiments;

FIG. 12 illustrates a third example use case of energy-harvestingrouting, in accordance with certain embodiments;

FIG. 13 illustrates a method in a node, in accordance with certainembodiments;

FIG. 14 is a block schematic of an exemplary wireless device, inaccordance with certain embodiments;

FIG. 15 is a block schematic of an exemplary network node, in accordancewith certain embodiments;

FIG. 16 is a block schematic of an exemplary radio network controller orcore network node, in accordance with certain embodiments;

FIG. 17 is a block schematic of an exemplary wireless device, inaccordance with certain embodiments; and

FIG. 18 is a block schematic of an exemplary network node, in accordancewith certain embodiments.

DETAILED DESCRIPTION

As described above, existing approaches (including interference-awarerouting) suffer from certain deficiencies. In interference-awarerouting, each relay on a route decodes its desired message (by treatingother signals as noise), re-encodes it and then forward. This relayoperation is referred to as decode-and-forward (DF). To minimizeinterference at the nodes, interference-aware routing establishes routesthat are as far from each other as possible. This approach, however,incurs significant limitation on network throughput at high load.Furthermore, because the transmission rate on every route is determinedby the minimum of all link-capacities on the route, one stronginterference on a path can drastically degrade the end-to-endperformance. Thus, there is a need for a more advanced coding schemethat can efficiently manage strong interference instead of simplytreating it as noise.

In contrast to an interference-aware routing approach, the presentdisclosure contemplates a transmission scheme in which operation at arelay is quantize-map-forward (QMF) or, more generally, noisy networkcoding (NNC) rather than DF. QMF is known in the art and described in S.Avestimehr, S. Diggavi, and D. Tse, “Wireless network information flow:A deterministic approach,” IEEE Trans. Inf. Theory, vol. 57, pp.1872-1905, April 2011., the entirety of which is hereby incorporated byreference as if fully set forth herein. NNC is known in the art anddescribed in S. Lim, Y. H. Kim, A. E. Gamal, and S. Chung, “NoisyNetwork Coding,” IEEE Trans. Inf. Theory, vol. 57, pp. 3132-3152, theentirety of which is hereby incorporated by reference as if fully setforth herein. According to certain embodiments described herein, routesare established via energy-harvesting routing.

For example, in certain embodiments a method in a node is disclosed. Thenode determines a first route from a first source node to a destination.The first route comprises one or more relay nodes, and may be a routehaving a shortest number of hops between the first source node and thedestination. The node determines an energy-harvesting routing metric.The energy-harvesting routing metric may be used to determine a secondroute from a second source node to the destination. For example, incertain embodiments the energy-harvesting routing metric may be amultiple input multiple output (MIMO) channel capacity or a function ofsignal-to-noise ratios (SNR). The node determines the second route fromthe second source node to the destination. The determined second routecomprises one or more relay nodes selected to maximize the determinedenergy-harvesting routing metric. In certain embodiments, maximizing theenergy-harvesting routing metric comprises maximizing an achievable ratebetween consecutive relay nodes.

As described in more detail below, in certain embodiments the node mayoptimize the determined first route based on the determined secondroute, the second route comprising one or more relay nodes selectedaccording to the determined energy-harvesting routing metric, whereinthe optimized first route maximizes the energy-harvesting routingmetric. In some cases, the node may optimize the determined second routebased on the optimized first route, wherein the optimized second routemaximizes the energy-harvesting routing metric. In some cases, the nodemay continue to optimize the determined first and second routes untilthe energy-harvesting metric for both the first and second routesexceeds a threshold value.

Energy-harvesting routing refers to a family of routing methods in whichthe metric is chosen such as to maximize interference between routes, orequivalently, to choose the routes to be as close as possible. Thisstands very much in contrast to interference-aware routing. Instead ofusing DF, each of the one or more relay nodes deploys QMF/NNC operation,in which the relay quantizes the observed signal, re-encodes it andforwards the signal. Because the relay node does not decode the message,there is no decoding constraint at the relay (unlike DF). In fact, anyinterfering signal that is received at the relay node will be forwardedthrough QMF and treated as a useful signal at the destination node. Forthis reason, QMF/NNC actually performs better when the network is denseand interference is higher. As such, as used herein, (and as may be forfully understood from the below description) an interfering signal canin some instances be useful, and the term interference as used hereintherefore refers to any mixture of two or more signals and interferingsignals refer to signals that mix with each other and not necessarilyharmful signals. A signal may be referred to as both an interferingsignal when it mixes with another signal, but the same interferingsignal may also be referred to as a useful signal when the mixing ofsignals does not adversely affect decoding of the signal.

This improved performance is shown in S. Hong, I. Maric and D. Hui, “ANovel Cooperative Strategy for Wireless Multihop Backhaul Networks,”included in U.S. Provisional Application 62/148,050 filed Apr. 15, 2015,the entirety of which is hereby incorporated by reference as if fullyset forth herein. Additional details are also shown in S. Hong, I. Maricand D. Hui, “A Novel Relaying Strategy for Wireless Multihop BackhaulNetworks,” IEEE Globecom, San Diego, 6-10 Dec. 2015 (also included inU.S. Provisional Application 62/148,050 filed Apr. 15, 2015), theentirety of which is hereby incorporated by reference as if fully setforth herein.

The various embodiments described herein can be exploited in any networkscenario in which data is sent through relays. Therefore, it applies towireless networks in general and particular applications such asmulti-hop backhaul, network-assisted D2D communications, cellularnetworks with relays, and any other suitable applications. One ofordinary skill in the art would realize that various communication nodes(e.g., UE or other station) could perform the various processesdescribed herein.

FIG. 1 is a diagram illustrating an embodiment of a wirelesscommunication network 100, in accordance with certain embodiments.Network 100 includes one or more UE(s) 110 (which may be interchangeablyreferred to as wireless devices 110), network node(s) 115 (which may beinterchangeably referred to as eNodeBs (eNBs) 115). UEs 110 maycommunicate with network nodes 115 over a wireless interface. Forexample, UE 110A may transmit wireless signals to one or more of networknodes 115, and/or receive wireless signals from one or more of networknodes 115. The wireless signals may contain voice traffic, data traffic,control signals, and/or any other suitable information. In someembodiments, an area of wireless signal coverage associated with anetwork node 115 may be referred to as a cell. In some embodiments, UEs110 may have device-to-device (D2D) capability. Thus, UEs 110 may beable to receive signals from and/or transmit signals directly to anotherUE. For example, UE 110A may be able to receive signals from and/ortransmit signals to UE 110B.

In certain embodiments, network nodes 115 may interface with a radionetwork controller. The radio network controller may control networknodes 115 and may provide certain radio resource management functions,mobility management functions, and/or other suitable functions. Incertain embodiments, the functions of the radio network controller maybe included in network node 115. The radio network controller mayinterface with a core network node. In certain embodiments, the radionetwork controller may interface with the core network node via aninterconnecting network. The interconnecting network may refer to anyinterconnecting system capable of transmitting audio, video, signals,data, messages, or any combination of the preceding. The interconnectingnetwork may include all or a portion of a public switched telephonenetwork (PSTN), a public or private data network, a local area network(LAN), a metropolitan area network (MAN), a wide area network (WAN), alocal, regional, or global communication or computer network such as theInternet, a wireline or wireless network, an enterprise intranet, or anyother suitable communication link, including combinations thereof.

In some embodiments, the core network node may manage the establishmentof communication sessions and various other functionalities for UEs 110.UEs 110 may exchange certain signals with the core network node usingthe non-access stratum layer. In non-access stratum signaling, signalsbetween UEs 110 and the core network node may be transparently passedthrough the radio access network. In certain embodiments, network nodes115 may interface with one or more network nodes over an internodeinterface. For example, network nodes 115A and 115B may interface overan X2 interface.

As described above, example embodiments of network 100 may include oneor more wireless devices 110, and one or more different types of networknodes capable of communicating (directly or indirectly) with wirelessdevices 110.

In some embodiments, the non-limiting term UE is used. UEs 110 describedherein can be any type of wireless device capable of communicating withnetwork nodes 115 or another UE over radio signals. UE 110 may also be aradio communication device, target device, D2D UE,machine-type-communication UE or UE capable of machine to machinecommunication (M2M), low-cost and/or low-complexity UE, a sensorequipped with UE, Tablet, mobile terminals, smart phone, laptop embeddedequipped (LEE), laptop mounted equipment (LME), USB dongles, CustomerPremises Equipment (CPE), etc. UE 110 may operate under either normalcoverage or enhanced coverage with respect to its serving cell. Theenhanced coverage may be interchangeably referred to as extendedcoverage. UE 110 may also operate in a plurality of coverage levels(e.g., normal coverage, enhanced coverage level 1, enhanced coveragelevel 2, enhanced coverage level 3 and so on). In certain embodiments,UE 110 may be configured to operation in out-of-network coveragescenarios.

Also, in some embodiments generic terminology, “radio network node” (orsimply “network node”) is used. It can be any kind of network node,which may comprise an aggregation node (AgN), a base station (BS), radiobase station, Node B, base station (BS), multi-standard radio (MSR)radio node such as MSR BS, evolved Node B (eNB), network controller,radio network controller (RNC), base station controller (BSC), relaynode, relay donor node controlling relay, base transceiver station(BTS), access point (AP), radio access point, transmission points,transmission nodes, Remote Radio Unit (RRU), Remote Radio Head (RRH),nodes in distributed antenna system (DAS), Multi-cell/multicastCoordination Entity (MCE), core network node (e.g., MSC, MME etc), O&M,OSS, SON, positioning node (e.g., E-SMLC), MDT, or any suitable networknode. A network node is an even more general term, which may be a radionetwork node or a core network node (e.g., TCE, MME, MDT node, MBMSnode) or even an external node (e.g., 3^(rd) party node, a node externalto the current network). Note that any radio network node is a networknode, but not any network node is a radio network node.

The terminology such as network node and UE should be considerednon-limiting and does in particular not imply a certain hierarchicalrelation between the two; in general “eNodeB” could be considered asdevice 1 and “UE” device 2, and these two devices communicate with eachother over some radio channel.

Example embodiments of UE 110, network nodes 115, and other networknodes (such as radio network controller or core network node) aredescribed in more detail below with respect to FIGS. 14-18.

Although FIG. 1 illustrates a particular arrangement of network 100, thepresent disclosure contemplates that the various embodiments describedherein may be applied to a variety of networks having any suitableconfiguration. As described in more detail below in relation to FIGS.2-13, network 100 may be a mesh network having any configuration andincluding any suitable number of source nodes, relay nodes (which may beinterchangeably referred to as relays), and destinations. Furthermore,network 100 may include any suitable number of UEs 110 and network nodes115, as well as any additional elements suitable to supportcommunication between UEs or between a UE and another communicationdevice (such as a landline telephone). Furthermore, although certainembodiments may be described as implemented in a Long Term Evolution(LTE) network, the embodiments may be implemented in any appropriatetype of telecommunication system supporting any suitable communicationstandards and using any suitable components, and are applicable to anyradio access technology (RAT) or multi-RAT systems in which the UEreceives and/or transmits signals (e.g., data). For example, the variousembodiments described herein may be applicable to LTE, LTE-Advanced,UMTS, HSPA, GSM, cdma2000, WiMax, WiFi, another suitable radio accesstechnology, or any suitable combination of one or more radio accesstechnologies. Although certain embodiments may be described in thecontext of wireless transmissions in the downlink, the presentdisclosure contemplates that the various embodiments are equallyapplicable in the uplink.

In the following description, numerous specific details are set forth.However, it is understood that the various embodiments described hereinmay be practiced without these specific details. In other instances,well-known circuits, structures and techniques have not been shown indetail in order not to obscure the understanding of this description.Those of ordinary skill in the art, with the included descriptions, willbe able to implement appropriate functionality without undueexperimentation.

References in the specification to “certain embodiments,” “oneembodiment,” “an embodiment,” “an example embodiment,” etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to implement suchfeature, structure, or characteristic in connection with otherembodiments whether or not explicitly described.

In the following, the terms “coupled” and “connected,” along with theirderivatives, may be used. It should be understood that these terms arenot intended as synonyms for each other. “Coupled” is used to indicatethat two or more elements, which may or may not be in direct physical orelectrical contact with each other, co-operate or interact with eachother. “Connected” is used to indicate the establishment ofcommunication between two or more elements that are coupled with eachother.

FIG. 2 illustrates an example wireless mesh network including multiplesource nodes and one destination, in accordance with certainembodiments. More specifically, FIG. 2 illustrates a plurality of sourcenodes 205 (e.g., source nodes 205A-D). As shown in FIG. 2, source node205A may be a first source node, source node 205B may be a second sourcenode, source node 205C may be a third source node, and source node 205Dmay be a fourth source node. FIG. 2 also illustrates destination node210 (which may be interchangeably referred to as destination 210 and/oraggregation node 210). FIG. 2 also illustrates a number of relay nodes215.

Source nodes 205A-D, destination node 210, and relay nodes 215 may beany suitable nodes. For example, in certain embodiments source nodes205A-D, destination node 210, and relay nodes 215 may comprise anysuitable combination of network nodes and/or wireless devices, such asnetwork nodes 115 and wireless devices 110 described above in relationto FIG. 1 and in more detail below with respect to FIGS. 14-18. As oneexample, in certain embodiments source nodes 205A-D may be wirelessdevices, such as wireless devices 110 described above in relation toFIG. 1, destination node 210 may be a network node (such as network node115 described above in relation to FIG. 1, for example an eNB, WLAN AP,an aggregation node, or any other suitable network node), and relaynodes 215 may be any suitable type of network nodes (such as networknodes 115 described above in relation to FIG. 1).

As described above, the various embodiments described herein may beapplicable to communication from multiple data sources (e.g., sourcenodes 205A-D) to a common destination (e.g., destination 210) through amesh/multi-hop network, as shown in FIG. 2. In the example of FIG. 2,data is sent from one or more of source nodes 205A-205B to destination210. The data sent from source nodes 205A-205D is sent via relays 215via multi-hop communications. The path from one of source nodes 205A-D(e.g., source node 205A) to destination 210 may include any suitablenumber of relay nodes 215. Although certain embodiments may beillustrated using two source nodes and a single destination, the presentdisclosure contemplates that the various embodiments are applicable toany suitable number of source nodes (including more than two sourcenodes), destination nodes (including more than one destination node),and relay nodes.

FIG. 3 illustrates an example of interference-aware routing. Morespecifically, FIG. 3 illustrates a plurality of source nodes 305 (e.g.,source nodes 305A-C). As shown in FIG. 3, source node 305A may be afirst source node (e.g., User 1), source node 305B may be a secondsource node (e.g., User 2), and source node 305C may be a third sourcenode (e.g., User 3). FIG. 3 also illustrates destination node 310.(which may be interchangeably referred to as destination 310 and/oraggregation node 310). FIG. 3 also illustrates a number of relay nodes315.

Source nodes 305A-C, destination node 310, and relay nodes 315 may beany suitable nodes. For example, in certain embodiments source nodes305A-C, destination node 310, and relay nodes 315 may comprise anysuitable combination of network nodes and/or wireless devices, such asnetwork nodes 115 and wireless devices 110 described above in relationto FIG. 1 and in more detail below with respect to FIGS. 14-18). As oneexample, in certain embodiments source nodes 305A-C may be wirelessdevices, such as wireless devices 110 described above in relation toFIG. 1. Destination node 310 may be a network node (such as network node115 described above in relation to FIG. 1, for example an eNB, WLAN AP,an aggregation node, or any other suitable network node), and relaynodes 315 may be any suitable type of network nodes (such as networknodes 115 described above in relation to FIG. 1).

In the example of FIG. 3, data is sent from one or more of source nodes305A-C to destination 310. The data sent from source nodes 305A-C issent via relays 315 via multi-hop communications. The path from one ofsource nodes 305A-C to destination 310 may include any suitable numberof relay nodes 315. In interference-aware routing (which may beinterchangeably referred to as interference-avoidance routing), eachrelay 315 along a route from one of source nodes 305A-C to destination310 may perform DF (i.e., each relay 315 decodes its desired message (bytreating other signals as noise), re-encodes it and then forwards italong the path). To minimize interference at the nodes,interference-aware routing establishes routes that are as far from eachother as possible. To illustrate, assume that each of source nodes305A-305C has data to send to destination 310. In the example of FIG. 3,the route from source node 305A to destination 310 includes relays 315Aand 315B, the route from source node 305B to destination 310 includesrelays 315C and 315D, and the route from source node 305C to destination310 includes relays 315E and 315F. Each of relays 315A-F perform DFoperation. As shown in the example of FIG. 3, the routes from each ofsource nodes 305A-C are selected to be as far from each other aspossible.

As described above, interference becomes a main limiting factor onnetwork throughput for wireless multi-hop backhaul network. Ininterference-aware routing, each relay 315 decodes its desired messageby treating other signals as noise. Interference-aware routingalgorithms aim to avoid inter-path interference. This approach incurssignificant limitation on network throughput at high load (i.e., thenumber of sources is large). This result is expected since it is nearlyimpossible to avoid all inter-path interference at high load.Furthermore, because the transmission rate on every route is determinedby the minimum of all link-capacities on the route, one stronginterference on a path can drastically degrade the end-to-endperformance.

FIG. 4 illustrates an example of energy-harvesting routing, inaccordance with certain embodiments. More specifically, FIG. 4illustrates a plurality of source nodes 405 (e.g., source nodes 405A-C).As shown in FIG. 4, source node 405A may be a first source node (e.g.,User 1), source node 405B may be a second source node (e.g., User 2),and source node 405C may be a third source node (e.g., User 3). FIG. 4also illustrates a destination node 410 (which may be interchangeablyreferred to as destination 410 and/or aggregation node 410). FIG. 4 alsoillustrates a number of relay nodes 415.

Source nodes 405A-C, destination node 410, and relay nodes 415 may beany suitable nodes. For example, in certain embodiments source nodes405A-C, destination 410, and relay nodes 415 may comprise any suitablecombination of network nodes and/or wireless devices, such as networknodes 115 and wireless devices 110 described above in relation to FIG. 1and in more detail below with respect to FIGS. 14-18. As one example, incertain embodiments source nodes 405A-C may be wireless devices, such aswireless devices 110 described above in relation to FIG. 1. Destinationnode 410 may be a network node (such as network node 115 described abovein relation to FIG. 1, for example an eNB, WLAN AP, an aggregation node,or any other suitable network node), and relay nodes 415 may be anysuitable type of network nodes (such as network nodes 115 describedabove in relation to FIG. 1). Data may be sent from one or more ofsource nodes 405A-C to destination 410. The data sent from source nodes405A-C is sent via relays 415 via multi-hop communications. The pathfrom one of source nodes 405A-C to destination 410 may include anysuitable number of relay nodes 415.

Energy-harvesting routing refers to a family of routing methods in whichthe metric is chosen to maximize interference between routes, orequivalently, to choose the routes to be as close as possible. Toillustrate, assume in the example of FIG. 4 that each of source nodes405A-C has data to send to destination 410. In the example of FIG. 4,the route from source node 405A to destination 410 includes relays 415Aand 415B, the route from source node 405B to destination 410 includesrelays 415C and 415D, and the route from source node 405C to destination410 includes relays 415E and 415F. As can be seen from FIG. 4, theroutes from source nodes 405A-C to destination 410 are chosen to be asclose together as possible.

Each of relays 415A-F performs QMF (or, more generally, NNC). In such acase, each relay 415 quantizes the observed signal, re-encodes it andforwards the signal toward the next node on the route (e.g., anotherrelay 415 or destination node 410). Because relays 415 do not decode themessage, there is no decoding constraint at relays 415 (unlike the DFoperation in interference-aware routing described above in relation toFIG. 3). In fact, any interfering signal that is received at a relaynode 415 will be forwarded through QMF and treated as a useful signal atdestination 410. This is in contrast to the interference-aware approachto routing described above, and for this reason, QMF/NNC actuallyperforms better when the network is dense and interference is higher.Energy-harvesting routing is described in more detail below in relationto FIGS. 5-8.

FIG. 5 illustrates a first step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments. More particularly, FIG. 5illustrates two source nodes S₁ 505A and S₂ 505B, destination 510, and aplurality of relay nodes 515A-F. Source nodes S₁ 505A and S₂ 505B,destination node 510, and relay nodes 515 may be any suitable nodes. Forexample, in certain embodiments source nodes S₁ 505A and S₂ 505B,destination node 510, and relay nodes 515 may comprise any suitablecombination of network nodes and/or wireless devices, such as networknodes 115 and wireless devices 110 described above in relation to FIG. 1and in more detail below with respect to FIGS. 14-18. As one example, incertain embodiments source nodes S₁ 505A and S₂ 505B may be wirelessdevices, such as wireless devices 110 described above in relation toFIG. 1. Destination node 510 may be a network node (such as network node115 described above in relation to FIG. 1, for example an eNB, WLAN AP,an aggregation node, or any other suitable network node), and relaynodes 515 may be any suitable type of network nodes (such as networknodes 115 described above in relation to FIG. 1). Data may be sent fromone or more of source nodes S₁ 505A and S₂ 505B to destination 510. Thedata sent from source nodes S₁ 505A and S₂ 505B is sent via relays 515via multi-hop communications. The path from one of source nodes S₁ 505Aand S₂ 505B to destination 510 may include any suitable number of relaynodes 515.

As described above, energy-harvesting routing refers to a family ofrouting methods in which the metric is chosen such as to maximizeinterference between routes, or equivalently, to choose the routes to beas close as possible. This can be done, for example, by choosing themetric that maximizes an achievable rate between every two consecutiverelay stages. The energy-harvesting routing metric may be any suitablemetric. For example, in certain embodiments the energy harvestingrouting metric may be a multiple input multiple output (MIMO) channelcapacity or a function of signal-to-noise ratio. Although the exampleembodiments of FIGS. 5-8 may be described in terms of MIMO channelcapacity as the energy-harvesting routing metric, the variousembodiments are not limited to such an example and any suitableenergy-harvesting metric may be used, including MIMO channel capacity, afunction of signal-to-noise ratio, and/or any other suitableenergy-harvesting routing metric or combination of energy-harvestingrouting metrics.

With respect to the example of FIGS. 5-8, for any choice of relays atthe two stages, the achievable rate between every two consecutive relaystages corresponds to a rate in a MIMO channel and can thus becalculated as described in detail below. In some cases, an approximationof such metric can be used to relays at each stage such that the signalpower received from the previous stage at each of these relays ismaximized, as is also explained in detail below.

An efficient method can be developed using the iterative algorithmdescribed in R. Draves, J. Padhye, and B. Zill, “Routing in Multi-Radio,Multi-Hop Wireless Mesh Networks,” in Proc. The Annual InternationalConference on Mobile Computing and Networking (MobiCom), pp. 114-128,Maui, Hi., September 2014. (“Routing in Multi-Radio”), the entirety ofwhich is hereby incorporated by reference as if fully incorporatedherein. More particularly, an efficient method can be developed usingthe iterative algorithm described in “Routing in Multi-Radio” byproperly modifying the routing criterion. In “Routing in Multi-Radio,”the algorithm establishes one route at a time while keeping otherpreviously established routes fixed, and repeats the process untillittle or no improvements in the sum throughput can be made. The routingcriterion maximizes each link-capacity on the route which is computed bytaking into account interference from all other routes.

For the energy-harvesting routing embodiments described herein, on theother hand, a relay (at stage k) is selected to maximize the MIMOcapacity defined by two consecutive stages k−1 and k. A description ofthis process for a network having two source nodes S₁ 505A and S₂ 505Bis provided in conjunction with the example of FIGS. 5-8. Although theprocess is described in the context of a network having two source nodesS₁ 505A and S₂ 505B and a single destination 510, the present disclosurecontemplates that the various embodiments are applicable to cases withmore than two sources and more than one destination. Generalization tothe case with more sources and/or destinations is described in moredetail below.

In the following description, the notation

_(MIMO)({R₁, R₂}, {R₃, R₄}) is used to denote the MIMO capacity inducedby two transmitters {R₁, R₂} and two receivers {R₃, R₄}. Initially, apath from S₁ 505A to destination 510 is established. The path from S₁505A to destination 510 may be established in any suitable manner. Forexample, in certain embodiments the path from S₁ 505A to destination 510is established so that the number of hops is minimized and eachlink-capacity along the route is maximized (namely, the received poweris maximized). This process closely follows the step that establishesthe initial route as described in “Routing in Multi-Radio” (incorporatedby reference above). As shown in FIG. 5, the route from source node S₁505A to destination 510 includes relays 515A and 515B. The relays 515Aand 515B on the path from S₁ 505A to destination 510 are denoted asR_(1,1) ¹, R_(1,2) ¹, respectively.

Next, based on the fixed route from S₁ 505A to destination 510, a secondroute from S₂ 505B to destination 510 is established. As shown in FIG.5, as part of the first step one or more first candidate relay nodes 515are determined. The first candidate relay nodes 515 are located within achosen communication range from S₂ 505B (these relays form theneighborhood of S₂) that have not been already chosen for other routes.In the example of FIG. 5, the first candidate relay nodes include relaynodes 515C-F. The communication range is a design parameter that can hedetermined in any suitable manner. For example, in certain embodimentsthe communication range may he determined as a function of the transmitpower where the transmit power should be larger than a threshold tosatisfy network connectivity. For example, let τ₁={R_(1,1), . . .,R_(1,|τ) ₁ _(|)} denote the set of such neighboring relays (i.e., first“candidate relays” of the first stage). For the j-th relay in τ₁, theMIMO capacity (i.e., routing metric) can be computed according toExpression 1 below:

_(MIMO)({S ₁ ,S ₂ },{R _(1,1) ¹ ,R _(1,j)}),  (1)where R_(1,1) ¹, denotes the first relay of the first route from S₁ 505Ato destination 510 (i.e., relay node 515A).

FIG. 6 illustrates a second step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments. As described above with respect toFIG. 5, the path from source node S₁ 505A to destination 510 includesrelay nodes 515A and 515B (denoted as R_(1,1) ¹, R_(1,2) ¹,respectively). With S₁, S₂, R_(1,1) ¹ fixed, a relay R_(1,j) for thesecond route from S₂ 505B to destination 510 is chosen to maximize theMIMO capacity according to Equation 2 below:

$\begin{matrix}{j_{1}^{*} = {\arg\;{\max\limits_{j \in {\lbrack{1:{\tau_{1}}}\rbrack}}{\mathcal{C}_{MIMO}( {\{ {S_{1},S_{2}} \},\{ {R_{1,1,}^{1}R_{1,j}} \}} )}}}} & (2)\end{matrix}$Thus, according to Equation 2 the candidate relay node that maximizesthe energy-harvesting routing metric is selected as the first relay nodeof the second route from source node S₂ 505B to destination 510. In theexample of FIG. 6, relay node 515C (denoted R_(1,1) ²) is selected asthe first rely of the second route.

FIG. 7 illustrates a third step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments. Like FIGS. 5 and 6, FIG. 7illustrates source nodes S₁ 505A and S₂ 505B, destination 510, and aplurality of relay nodes 515A-F. As described above with respect toFIGS. 5 and 6, the path from source node S₁ 505A to destination 510includes relay nodes 515A and 515B (denoted as R_(1,1) ¹, R_(1,2) ¹,respectively) and relay node 515C (denoted as R_(1,1) ²) has beenselected as the first relay node of the second route from source node S₂505B to destination node 510.

In the third step illustrated in FIG. 7, one or more second candidaterelay nodes 615 are determined from which the second relay node of thesecond route from source node S₂ 505B to destination 510 may beselected. In the example of FIG. 7, the one or more second candidaterelay nodes include relay nodes 615A-C. The second candidate relay nodes615A-C are located within a communication range of the selected firstrelay node 515C of the second route (denoted as R_(1,1) ²). For example,let R_(1,1) ²=R_(1,j) ₁ _(*) . At the third step, the method finds thecandidate relays of the second stage denoted by τ₂={R_(2,1), . . . ,R_(2,|τ) ₂ _(|)}. The second relay node of the second route, R_(2,j) isselected from the one or more second candidate relays to maximize therouting metric according to Equation 3 below:

$\begin{matrix}{j_{2}^{*} = {\arg\mspace{11mu}{\max\limits_{j \in {\lbrack{1:{\tau_{2}}}\rbrack}}{{\mathcal{C}_{MIMO}( {\{ {R_{1,1,}^{1},R_{1,1,}^{2}} \},\{ {R_{1,2,}^{1}R_{2,j}} \}} )}.}}}} & (3)\end{matrix}$By setting R_(1,2) ²=R_(2,j) _(z) _(*) , the route from source node S₂505B to destination 510 can be established. In the example of FIG. 7,relay node 615A (denoted R_(1,2) ²) is selected as the second relay ofthe second route.

FIG. 8 illustrates a fourth step of energy-harvesting routing toestablish two routes from two source nodes to a destination node, inaccordance with certain embodiments. As shown in FIG. 8 (and describedabove in relation to FIGS. 5-7), the route from source node S₁ 505A todestination 510 includes relay nodes 515A and 515B (denoted as R_(1,1)¹, R_(1,2) ¹, respectively). The route from node S₂ 505B to destination510 includes relay nodes 515C and 615A (denoted as R_(1,1) ² and R_(1,2)², respectively). As described above, relay nodes 515C and 615A wereselected to maximize the energy-harvesting metric (which, in the exampleof FIGS. 5-8, is a MIMO channel capacity).

In certain embodiments, the method is iterative. Thus, at the fourthstep illustrated in FIG. 8, the process may be repeated to optimize theroutes until little or no improvements in the sum throughput can bemade. In other words, having established the fixed route from sourcenode S₂ 505B to destination 510, the route from source node S₁ 505A todestination 510 can be optimized to maximize the energy-harvestingmetric. For example, for the route from source node S₁ 505A todestination 510, one or more third candidate relay nodes may bedetermined. The one or more third candidate relay nodes may be within acommunication range of source node S₁ 505A. Which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric is determined. The determination of which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric may be based on the energy-harvesting routing metric of sourcenode S₁ 505A, source node S₂ 505B, and the first relay node 515C(denoted R_(1,1) ²) of the second route. A third candidate relay nodethat maximizes the energy-harvesting routing metric is selected as a newfirst relay node of the first route (i.e., the route from source node S₁505A to destination 510). In some cases, the new first relay node of thefirst route may be the same relay node originally selected as the firstrelay node of the first route (e.g., relay node 515A) if it maximizesthe energy-harvesting metric. In other cases, the new first relay nodeof the first route may be a different relay node from the relay nodeoriginally selected as the first relay node of the first route.

Then, one or more fourth candidate relay nodes are determined, thefourth candidate relay nodes located within a communication range of thenew first relay node of the first route. The method determines which ofthe one or more fourth candidate relay nodes maximizes theenergy-harvesting routing metric. The determination of which of the oneor more fourth candidate relay nodes maximizes the energy-harvestingrouting metric is based on the energy-harvesting routing metric of thenew first relay node of the first route, the first relay node 515C(denoted R_(1,1) ²) of the second route, and the second relay node 615A(denoted R_(1,2) ²) of the second route. A fourth candidate relay nodethat maximizes the energy-harvesting routing metric is selected as a newsecond relay node of the first route.

Thus, given the fixed route from source node S₂ 505B to destination 510,the route from source node S₁ 505A to destination 510 can be updated.This process can then be repeated to update the second route. Forexample, the updated route from source node S₁ 505A to destination 510can be used to update the route from source node S₂ 505B to destination510 according to the steps described above. This process can be repeateduntil little or no improvements in the sum throughput can be made. Forexample, in certain embodiments the determined first and second routesmay continue to be optimized until the energy-harvesting routing metricfor both the first and second routes exceeds a threshold value.

As described above, the energy-harvesting routing metric may be anysuitable metric. For example, the energy-harvesting routing metric maybe a MIMO channel capacity. However, the various embodiments describedherein are not limited to such an example. To illustrate, consider thefollowing scenario in which the energy-harvesting routing metric is afunction of SNR. Using the example of FIGS. 5-8, let H_(j) denote the2×2 channel matrix between the two transmitters {S₁, S₂} and the tworeceivers {R_(1,1) ¹, R_(1,j)} for R_(1,j)ϵτ₁ i.e.,

${H_{j} = \begin{bmatrix}h_{11} & h_{12} \\h_{j\; 1} & h_{j\; 2}\end{bmatrix}},$where h_(i1) denotes the channel from S_(i) to R_(1,1) ¹, along theestablished first route and h_(ji) denotes the channel from S_(i) to acandidate relay R_(1,j)ϵτ₁. Assuming that the transmit power is SNR(i.e., in a noise-dominated system, the noise power is constant, so theSNR is proportional to transmit or receive power; in other words, thenoise power is unity and transmit or receive power is equal to SNRbecause the SNR denominator is 1 for these conditions), then

_(MIMO)({S ₁ ,S ₂ },{R _(1,1) ¹ ,R _(1,j)})=log det(I+SNR H _(j) H _(j)^(H))≤_((α))log(1+(|h ₁₁|² +|h ₁₂|²)SNR)+log(1+(|h _(j1)|² +|h_(j2)|²)SNR)where (a) follows from the Hadamard's inequality and equality isachieved if the two columns of H_(j) are orthogonal. Thus, the obtainedupper bound is maximized by choosing a relay R_(1,j) to maximizeSNRr_(j)=(|h_(j1)|²+|h_(j2)|²)SNR. SNRr_(j) is proportional to the powerof the signal received from S₁ and S₂ at the R_(1,j). Thus, SNRr_(j) canbe used as an energy-harvesting routing metric approximating the MIMOcapacity routing metric in the iterative method described above inrelation to FIGS. 5-8. This also implies that the energy-harvestingrouting tends to choose a relay such that the signal power received fromthe previous stage is maximized.

For interference-aware routing (based on DF), confining tonearest-neighbor transmissions maximizes the network throughput bymitigating the impact of inter-route interference. This is described inA. Ozgur, O. Leveque, and D. Tse, “Operating Regimes of Large WirelessNetworks,” Foundations and Trends in Networking, 2011, the entirety ofwhich is hereby incorporated by reference as though it had been fullyset forth herein. This approach, however, increases the number of hopsto reach a destination, thereby yielding long end-to-end delay. For theenergy-harvesting routing approach, on the other hand, longer one-hoptransmission (i.e., using a higher transmit power subject to a transmitpower constraint) increases the network throughput by decreasing thenumber of relay stages. This is due to the fact that, when relays useQMF, the throughput degrades logarithmically with the number of stagesK. Thus, the energy-harvesting routing can be more suitable for thesystems with a delay constraint due to a shorter end-to-end delaycompared to the interference-aware routing.

The various embodiments described herein can be extended to wirelessbackhaul networks with multiple destinations (or aggregation nodes(AgNs)). For example, assume a scenario in which there are M aggregationnodes. A subnetwork i can be defined consisting of AgN i and theassociated sources and relays for i=1, . . . , M. Each subnetwork can beestablished via energy-harvesting routing. Then, the proposedtransmission scheme can be applied to each subnetwork separately. Inthis case, there exists inevitable interference caused by the relaysassociated with different subnetworks. Such interference can be referredto as inter-network interference. Due to the use of energy-harvestingrouting, each subnetwork spans a narrow area over the entire networksince in order to exploit interference, the routes are chosen as closelyas possible (as described above with respect to FIGS. 4-8). For theinterference-aware routing, on the other hand, each subnetwork spans awide area over the whole network in order to avoid the inter-routeinterference (see description of FIG. 3 above). Therefore, theenergy-harvesting routing is much more efficient in avoiding theinter-network interference than the interference-aware routing. Whenusing the proposed scheme for multiple destination (i.e., AgNs), theenergy-harvesting routing further improves the performance compared withthe interference-aware routing.

In certain embodiments, energy-harvesting routing can be used toestablish each subnetwork and the interference-aware routing can be usedto avoid inter-network interference. For example, in some cases onesubnetwork is established at a time while keeping other previouslyestablished subnetworks fixed, and repeats the process until little orno improvements in the sum throughput can be made. For the fixedsubnetworks i for iϵ{1, . . . , M}\{j}, a subnetwork j can beestablished as follows. Interference-aware routing is performed toestablish the first route of a subnetwork j, where each link-capacity onthe route is computed by taking into account interference from all othersubnetworks. Given the first route, energy-harvesting routing can beperformed to establish the subnetwork j.

Routes that roots from different sources may in general have differentnumbers of hops due to the various source-destination distances. Such anetwork is referred to as an asymmetric layered network. In certainembodiments, this issue can be minimized by grouping the sources thatare closely located and serving them simultaneously, which can be viewedas user scheduling. Furthermore, this approach can maximize theenergy-harvesting gain since it is likely to produce a path such thatthe relays in each stage are closely located and hence each relay (usingQMF) can collect more broadcasted energy.

Although routes can have different number of hops, the proposed schemeof energy-harvesting routing can be applied to such asymmetric layerednetworks. The consequence of having some routes shorter than the otherswill be that the relay stages will contain a different number of relays.The details are described in “A Novel Cooperative Strategy for WirelessMultihop Backhaul Networks”, included in U.S. Provisional Application62/148,050 filed Apr. 15, 2015 and incorporated by reference in itsentirety above.

The various embodiments described herein can substantially improve thedata throughput over the conventional (single-route) routing solution.FIGS. 9 and 10 illustrate performance comparisons betweenenergy-harvesting routing and interference-aware routing that wereobtained via simulation. As can be seen from FIGS. 9 and 10, significantperformance gains can be achieved with the various embodiments describedherein.

FIG. 9 illustrates a performance comparison of energy-harvesting routingand interference-aware routing for three relay stages and four datasources; in accordance with certain embodiments. More particularly, FIG.9 illustrates the achievable rate per user (bits per channel use) forSNR [dB] for the proposed scheme (i.e., energy-harvesting routing) andmulti-hop routing (MR). As can be seen from FIG. 9, energy-harvestingrouting outperforms MR and has a larger performance gain as SNRincreases. This is because the strong interference limits theperformance of the MR while it further improves the performance of theproposed scheme.

FIG. 10 illustrates a performance comparison of energy-harvestingrouting and interference-aware routing for signal-to-noise ratio of 20dB, in accordance with certain embodiments. More particularly, FIG. 10illustrates the achievable rate per user (bits per channel use) for thenumber of relay stages (K) for the proposed scheme and MR for a numberof scenarios involving different numbers of data sources (i.e., users)L. Specifically, FIG. 10 illustrates the achievable rate per user forscenarios having 2 data sources, 10 data sources, and 20 data sources.From FIG. 10, it can be seen that in contrast to the MR, the performanceof the proposed scheme is improved as the number of users L increases.

FIGS. 11A and 11B illustrate two example use cases for energy-harvestingrouting, in accordance with certain embodiments. More particularly, FIG.11A illustrates an indoors scenario (for example, inside a home) havinga plurality of access nodes 1115. Similarly, FIG. 11B illustratesanother indoors scenario (for example, inside a home) having a pluralityof access nodes 1115 forming a wireless backhaul (mesh network). Incertain embodiments, the plurality of access nodes 1115 may serve asrelay nodes. Using the methods described above with respect to FIGS.1-10 and below with respect to FIG. 13, routes from one or more sourcesto one or more destinations (e.g., an aggregation node such asdestination 510 described above in relation to FIGS. 5-8) may beestablished using access nodes 1115 as relay nodes selected to maximizean energy-harvesting routing metric.

FIG. 12 illustrates a third example use case of energy-harvestingrouting, in accordance with certain embodiments. More particularly, FIG.12 illustrates an outdoor wireless backhaul (mesh) network having aplurality of sources (i.e., users) 1205, one or more destinations (i.e.,aggregation nodes) 1210, and a plurality of access nodes 1215 that canserve as relay nodes. Using the methods described above with respect toFIGS. 1-10 and below with respect to FIG. 13, routes from one or moresources 1205 to one or more destinations 1210 (e.g., an aggregationnode) may be established using access nodes 1215 as relay nodes selectedto maximize an energy-harvesting routing metric.

To illustrate, assume that users 1205A and 1205B have data to transmitto aggregation node (i.e., destination) 1210. Using the variousembodiments described herein, a first route may be determined from afirst source node 1205A to aggregation node 1210. The first route mayinclude one or more access nodes 1215 acting as relay nodes. In somecases, the determined first route may be a route having a shortestnumber of hops between first source node 1205A and aggregation node1210. An energy-harvesting routing metric may be determined for use indetermining a second route from a second source node 1205B toaggregation node 1210. A second route from second source node 1205B toaggregation node 1210 is then determined. The determined second routeincludes one or more relay nodes 1215 selected to maximize thedetermined energy-harvesting routing metric.

The determined first route from source node 1205A to aggregation node1210 may then be optimized based on the determined second route fromsource node 1205B to aggregation node 1210 to maximize theenergy-harvesting routing metric. The determined second route fromsource node 1205B to aggregation node 1210 may then be optimized basedon the optimized first route to maximize the energy-harvesting routingmetric. This process may be repeated, continuing to optimize thedetermined first and second routes until the energy-harvesting routingmetric for both the first and second routes exceeds a threshold value.

FIG. 13 illustrates a method in a node 1300, in accordance with certainembodiments. The method begins at step 1304, where the node determines afirst route from a first source node to a destination, the first routecomprising one or more relay nodes. In certain embodiments, thedetermined first route may comprise a route having a shortest number ofhops between the first source node and the destination. In certainembodiments, the relay nodes perform noisy network coding.

At step 1308, the node determines an energy-harvesting routing metric,the energy-harvesting routing metric for use in determining a secondroute from a second source node to the destination. In certainembodiments, the energy-harvesting routing metric may be a multipleinput multiple output (MIMO) channel capacity. In certain embodiments,the energy-harvesting routing metric may be a function ofsignal-to-noise ratios. The energy-harvesting metric may be determinedto maximize interference between routes.

At step 1312, the node determines the second route from the secondsource node to the destination, the determined second route comprisingone or more relay nodes selected to maximize the determinedenergy-harvesting routing metric. In certain embodiments, maximizing theenergy-harvesting routing metric may comprise maximizing an achievablerate between consecutive relay nodes. Determining the second route fromthe second source node to the destination may comprise: determining oneor more first candidate relay nodes, the first candidate relay nodeslocated within a communication range of the second source node;determining which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first source node, the secondsource node, and a first relay node of the first route; and selecting afirst candidate relay node that maximizes the energy-harvesting routingmetric as the first relay node of the second route.

In certain embodiments, the first route and the second route maycomprise different numbers of relay nodes. In certain embodiments, themethod may further comprise determining one or more second candidaterelay nodes, the second candidate relay nodes located within acommunication range of the selected first relay node of the secondroute. The method may comprise determining which of the one or moresecond candidate relay nodes maximizes the energy-harvesting routingmetric, wherein the determination of which of the one or more secondcandidate relay nodes maximizes the energy-harvesting routing metric isbased on energy-harvesting routing metrics of the first relay node ofthe first route, the first relay node of the second route, and a secondrelay node of the first route. The method may comprise selecting asecond candidate relay node that maximizes the energy-harvesting routingmetric as the second relay node of the second route.

In certain embodiments, the method may comprise optimizing thedetermined first route based on the determined second route, the secondroute comprising one or more relay nodes selected according to thedetermined energy-harvesting routing metric, wherein the optimized firstroute maximizes the energy-harvesting routing metric. Optimizing thedetermined first route based on the determined second route maycomprise: determining one or more third candidate relay nodes, the thirdcandidate relay nodes located within a communication range of the firstsource node; determining which of the one or more third candidate relaynodes maximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more third candidate relay nodesmaximizes the energy-harvesting routing metric is based on theenergy-harvesting routing metric of the first source node, the secondsource node, and a first relay node of the second route; and selecting athird candidate relay node that maximizes the energy-harvesting routingmetric as a new first relay node of the first route.

In certain embodiments, the method may comprise determining one or morefourth candidate relay nodes, the fourth candidate relay nodes locatedwithin a communication range of the new first relay node of the firstroute; determining which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric is based on theenergy-harvesting routing metric of the new first relay node of thefirst route, the first relay node of the second route, and the secondrelay node of the second route; and selecting a fourth candidate relaynode that maximizes the energy-harvesting routing metric as a new secondrelay node of the first route.

In certain embodiments, the method may comprise optimizing thedetermined second route based on the optimized first route, wherein theoptimized second route maximizes the energy-harvesting routing metric.The method may comprise continuing to optimize the determined first andsecond routes until the energy-harvesting routing metric for both thefirst and second routes exceeds a threshold value.

In certain embodiments, the method may comprise defining a plurality ofsubnetworks, the defined plurality of subnetworks comprising at least afirst subnetwork comprising the destination and the first and secondsource nodes and a second subnetwork comprising a second destination anda plurality of source nodes associated with the second destination, theplurality of source nodes including at least one additional source node.The method may comprise determining a first route for the secondsubnetwork from one of the plurality of source nodes associated with thesecond destination to the second destination, the first route for thesecond subnetwork comprising one or more relay nodes. In certainembodiments, the first route for the second subnetwork may be determinedusing interference-aware routing. The method may comprise determining asecond route for the second subnetwork from another of the plurality ofsource nodes associated with the second destination to the seconddestination, the determined second route for the second subnetworkcomprising one or more relay nodes selected to maximize the determinedenergy-harvesting routing metric. The method may comprise optimizing thedetermined first route for the second subnetwork based on the determinedsecond route for the second subnetwork, the second route for the secondsubnetwork comprising one or more relay nodes selected according to thedetermined energy-harvesting routing metric, wherein the optimized firstroute for the second subnetwork maximizes the energy-harvesting routingmetric.

FIG. 14 is a block schematic of an exemplary wireless device, inaccordance with certain embodiments. Wireless device 110 may refer toany type of wireless device communicating with a node and/or withanother wireless device in a cellular or mobile communication system.Examples of wireless device 110 include a mobile phone, a smart phone, aPDA (Personal Digital Assistant), a portable computer (e.g., laptop,tablet), a sensor, a modem, a machine-type-communication (MTC)device/machine-to-machine (M2M) device, laptop embedded equipment (LEE),laptop mounted equipment (LME), USB dongles, a D2D capable device, oranother device that can provide wireless communication. A wirelessdevice 110 may also be referred to as UE, a station (STA), a device, ora terminal in some embodiments. Wireless device 110 includes transceiver1410, processor 1420, and memory 1430. In some embodiments, transceiver1410 facilitates transmitting wireless signals to and receiving wirelesssignals from network node 115 (e.g., via antenna 1440), processor 1420executes instructions to provide some or all of the functionalitydescribed above as being provided by wireless device 110, and memory1430 stores the instructions executed by processor 1420. In someembodiments, wireless device 110 may optionally comprise a satellitepositioning system (e.g. GPS) receiver that can be used to determine theposition and speed of movement of the wireless device 110.

Processor 1420 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions ofwireless device 110, such as the functions of wireless device 110described above in relation to FIGS. 1-13. In some embodiments,processor 1420 may include, for example, one or more computers, one ormore central processing units (CPUs), one or more microprocessors, oneor more applications, one or more application specific integratedcircuits (ASICs), one or more field programmable gate arrays (FPGAs)and/or other logic. To make use of discontinuous reception (DRX),processor 1420 can be configured to deactivate transceiver 1410 forspecified lengths of time.

Memory 1430 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 1430include computer memory (for example, Random Access Memory (RAM) or ReadOnly Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information, data, and/or instructions that may beused by processor 1420.

A wireless device 110 may store and transmit (internally and/or withother electronic devices over a network) code (composed of softwareinstructions) and data using machine-readable media, such asnon-transitory machine-readable media (e.g., machine-readable storagemedia such as magnetic disks; optical disks; read only memory; flashmemory devices; phase change memory) and transitory machine-readabletransmission media (e.g., electrical, optical, acoustical or other formof propagated signals—such as carrier waves, infrared signals). Inaddition, such devices include hardware such as a set of one or moreprocessors (e.g., processor 1420) coupled to one or more othercomponents, such as one or more non-transitory machine-readable media(to store code and/or data) (e.g., memory 1430), user input/outputdevices (e.g., a keyboard, a touchscreen, and/or a display), and networkconnections (to transmit code and/or data using propagating signals).The coupling of the set of processors and other components is typicallythrough one or more busses and bridges (also termed as bus controllers).Thus, a non-transitory machine-readable medium of a given wirelessdevice 110 typically stores instructions for execution on one or moreprocessors of that wireless device. One or more parts of an embodimentdescribed herein may be implemented using different combinations ofsoftware, firmware, and/or hardware.

Other embodiments of wireless device 110 may include additionalcomponents beyond those shown in FIG. 14 that may be responsible forproviding certain aspects of the wireless device's functionality,including any of the functionality described above and/or any additionalfunctionality (including any functionality necessary to support thesolution described above). As just one example, wireless device 110 mayinclude input devices and circuits, output devices, and one or moresynchronization units or circuits, which may be part of the processor1420. Input devices include mechanisms for entry of data into wirelessdevice 110. For example, input devices may include input mechanisms,such as a microphone, input elements, a display, etc. Output devices mayinclude mechanisms for outputting data in audio, video and/or hard copyformat. For example, output devices may include a speaker, a display,etc.

FIG. 15 is a block schematic of an exemplary network node, in accordancewith certain embodiments. Network node 115 may be any type of radionetwork node or any network node that communicates with a UE and/or withanother network node. Examples of network node 115 include an eNodeB(e.g., a macro eNB or a micro eNB), a node B, a base station, a wirelessaccess point (e.g., a Wi-Fi access point), a low power node, a basetransceiver station (BTS), relay, donor node controlling relay,transmission points, transmission nodes, remote RF unit (RRU), remoteradio head (RRH), multi-standard radio (MSR) radio node such as MSR BS,a router, a switch, a bridge, nodes in distributed antenna system (DAS),O&M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any othersuitable network node. Network nodes 115 may be deployed throughoutnetwork 100 as a homogenous deployment, heterogeneous deployment, ormixed deployment. A homogeneous deployment may generally describe adeployment made up of the same (or similar) type of network nodes 115and/or similar coverage and cell sizes and inter-site distances. Aheterogeneous deployment may generally describe deployments using avariety of types of network nodes 115 having different cell sizes,transmit powers, capacities, and inter-site distances. For example, aheterogeneous deployment may include a plurality of low-power nodesplaced throughout a macro-cell layout. Mixed deployments may include amix of homogenous portions and heterogeneous portions. It will beappreciated that although a macro eNB will not in practice be identicalin size and structure to a micro eNB, for the purposes of illustration,the base stations 115 are assumed to include similar components.

Network node 115 may include one or more of transceiver 1510, processor1520, memory 1530, and network interface 1540. In some embodiments,transceiver 1510 facilitates transmitting wireless signals to andreceiving wireless signals from wireless device 110 (e.g., via antenna1550), processor 1520 executes instructions to provide some or all ofthe functionality described above as being provided by a network node115, memory 1530 stores the instructions executed by processor 1520, andnetwork interface 1540 communicates signals to backend networkcomponents, such as a gateway, switch, router, Internet, Public SwitchedTelephone Network (PSTN), core network nodes or radio networkcontrollers 130, etc.

Processor 1520 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions ofnetwork node 115, such as those described above in relation to FIGS.1-13 above. In some embodiments, processor 1520 may include, forexample, one or more computers, one or more central processing units(CPUs), one or more microprocessors, one or more applications, and/orother logic.

Memory 1530 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 1530include computer memory (for example, Random Access Memory (RAM) or ReadOnly Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information.

In some embodiments, network interface 1540 is communicatively coupledto processor 1520 and may refer to any suitable device operable toreceive input for network node 115, send output from network node 115,perform suitable processing of the input or output or both, communicateto other devices, or any combination of the preceding. Network interface1540 may include appropriate hardware (e.g., port, modem, networkinterface card, etc.) and software, including protocol conversion anddata processing capabilities, to communicate through a network. Incertain embodiments, network interface 1540 may also include componentsand/or circuitry (such as an eNodeB interface) for allowing network node115 to exchange information with other network nodes 115 (for examplevia an X2 interface) and components and/or circuitry (such as a corenetwork interface) for allowing network node 115 to exchange informationwith nodes in the core network (for example via the S1 interface).

In certain embodiments, network node 115 may be referred to as a networkdevice or apparatus. A network device or apparatus (e.g., a router,switch, bridge) is a piece of networking equipment, including hardwareand software, which communicatively interconnects other equipment on thenetwork (e.g., other network devices, end stations). Some networkdevices are “multiple services network devices” that provide support formultiple networking functions (e.g., routing, bridging, switching, Layer2 aggregation, session border control, Quality of Service, and/orsubscriber management), and/or provide support for multiple applicationservices (e.g., data, voice, and video). Subscriber end stations (e.g.,servers, workstations, laptops, netbooks, palm tops, mobile phones,smartphones, multimedia phones, Voice Over Internet Protocol (VOIP)phones, user equipment, terminals, portable media players, GPS units,gaming systems, set-top boxes) access content/services provided over theInternet and/or content/services provided on virtual private networks(VPNs) overlaid on (e.g., tunneled through) the Internet. The contentand/or services are typically provided by one or more end stations(e.g., server end stations) belonging to a service or content provideror end stations participating in a peer to peer service, and mayinclude, for example, public webpages (e.g., free content, store fronts,search services), private webpages (e.g., username/password accessedwebpages providing email services), and/or corporate networks over VPNs.Typically, subscriber end stations are coupled (e.g., through customerpremise equipment coupled to an access network (wired or wirelessly)) toedge network devices, which are coupled (e.g., through one or more corenetwork devices) to other edge network devices, which are coupled toother end stations (e.g., server end stations). One of ordinary skill inthe art would realize that any network device, end station or othernetwork apparatus can perform the functions described herein.

Other embodiments of network node 115 may include additional componentsbeyond those shown in FIG. 15 that may be responsible for providingcertain aspects of the radio network node's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). The various different types of network nodes mayinclude components having the same physical hardware but configured(e.g., via programming) to support different radio access technologies,or may represent partly or entirely different physical components. Forexample, network nodes 115 for use in other types of network (e.g.,UTRAN or WCDMA RAN) will include similar components to those shown inFIG. 15 and appropriate interface circuitry for enabling communicationswith the other network nodes in those types of networks (e.g., othernetwork nodes (such as base stations), mobility management nodes and/ornodes in the core network).

FIG. 16 is a block schematic of an exemplary radio network controller orcore network node 130, in accordance with certain embodiments. Examplesof network nodes can include a mobile switching center (MSC), a servingGPRS support node (SGSN), a mobility management entity (MME), a radionetwork controller (RNC), a base station controller (BSC), and so on.The radio network controller or core network node 130 includes processor1620, memory 1630, and network interface 1640. In some embodiments,processor 1620 executes instructions to provide some or all of thefunctionality described above as being provided by the network node,memory 1630 stores the instructions executed by processor 1620, andnetwork interface 1640 communicates signals to any suitable node, suchas a gateway, switch, router, Internet, Public Switched TelephoneNetwork (PSTN), network nodes 115, radio network controllers or corenetwork nodes 130, etc.

Processor 1620 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions of theradio network controller or core network node 130. In some embodiments,processor 1620 may include, for example, one or more computers, one ormore central processing units (CPUs), one or more microprocessors, oneor more applications, and/or other logic.

Memory 1630 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 1630include computer memory (for example, Random Access Memory (RAM) or ReadOnly Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information.

In some embodiments, network interface 1640 is communicatively coupledto processor 1620 and may refer to any suitable device operable toreceive input for the network node, send output from the network node,perform suitable processing of the input or output or both, communicateto other devices, or any combination of the preceding. Network interface1640 may include appropriate hardware (e.g., port, modem, networkinterface card, etc.) and software, including protocol conversion anddata processing capabilities, to communicate through a network.

Other embodiments of the network node may include additional componentsbeyond those shown in FIG. 16 that may be responsible for providingcertain aspects of the network node's functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the solution describedabove).

FIG. 17 is a block schematic of an exemplary wireless device, inaccordance with certain embodiments. Wireless device 110 may include oneor more modules. For example, wireless device 110 may include adetermining module 1710, a communication module 1720, a receiving module1730, an input module 1740, a display module 1750, and any othersuitable modules. Wireless device 110 may perform the energy-harvestingrouting methods described above with respect to FIGS. 1-13.

Determining module 1710 may perform the processing functions of wirelessdevice 110. For example, determining module 1710 may determine a firstroute from a first source node to a destination, the first routecomprising one or more relay nodes. As another example, determiningmodule 1710 may determine an energy-harvesting routing metric, theenergy-harvesting routing metric for use in determining a second routefrom a second source node to the destination. As still another example,determining module 1710 may determine the second route from the secondsource node to the destination, the determined second route comprisingone or more relay nodes selected to maximize the determinedenergy-harvesting routing metric.

In some cases, determining module 1710 may determine the second routefrom the second source node to the destination by: determining one ormore first candidate relay nodes, the first candidate relay nodeslocated within a communication range of the second source node;determining which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first source node, the secondsource node, and a first relay node of the first route; and selecting afirst candidate relay node that maximizes the energy-harvesting routingmetric as the first relay node of the second route.

As yet another example, determining module 1710 may: determine one ormore second candidate relay nodes, the second candidate relay nodeslocated within a communication range of the selected first relay node ofthe second route; determine which of the one or more second candidaterelay nodes maximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more second candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first relay node of the firstroute, the first relay node of the second route, and a second relay nodeof the first route; and select a second candidate relay node thatmaximizes the energy-harvesting routing metric as the second relay nodeof the second route.

As another example, determining module 1710 may optimize the determinedfirst route based on the determined second route, the second routecomprising one or more relay nodes selected according to the determinedenergy-harvesting routing metric, wherein the optimized first routemaximizes the energy-harvesting routing metric. In some cases,determining module 1710 may optimize the determined first route based onthe determined second route by determining one or more third candidaterelay nodes, the third candidate relay nodes located within acommunication range of the first source node; determining which of theone or more third candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric is based on the energy-harvesting routing metric of the firstsource node, the second source node, and a first relay node of thesecond route; and selecting a third candidate relay node that maximizesthe energy-harvesting routing metric as a new first relay node of thefirst route.

As another example, determining module 1710 may: determine one or morefourth candidate relay nodes, the fourth candidate relay nodes locatedwithin a communication range of the new first relay node of the firstroute; determine which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric is based on theenergy-harvesting routing metric of the new first relay node of thefirst route, the first relay node of the second route, and the secondrelay node of the second route; and select a fourth candidate relay nodethat maximizes the energy-harvesting routing metric as a new secondrelay node of the first route.

As still another example, determining module 1710 may optimize thedetermined second route based on the optimized first route, wherein theoptimized second route maximizes the energy-harvesting routing metric.As another example, determining module 1710 may continue to optimize thedetermined first and second routes until the energy-harvesting routingmetric for both the first and second routes exceeds a threshold value.

As yet another example, determining module 1710 may: define a pluralityof subnetworks, the defined plurality of subnetworks comprising at leasta first subnetwork comprising the destination and the first and secondsource nodes and a second subnetwork comprising a second destination anda plurality of source nodes associated with the second destination, theplurality of source nodes including at least one additional source node;determine a first route for the second subnetwork from one of theplurality of source nodes associated with the second destination to thesecond destination, the first route for the second subnetwork comprisingone or more relay nodes; determine a second route for the secondsubnetwork from another of the plurality of source nodes associated withthe second destination to the second destination, the determined secondroute for the second subnetwork comprising one or more relay nodesselected to maximize the determined energy-harvesting routing metric;and optimize the determined first route for the second subnetwork basedon the determined second route for the second subnetwork, the secondroute for the second subnetwork comprising one or more relay nodesselected according to the determined energy-harvesting routing metric,wherein the optimized first route for the second subnetwork maximizesthe energy-harvesting routing metric.

Determining module 1710 may include or be included in one or moreprocessors, such as processor 1420 described above in relation to FIG.14. Determining module 1710 may include analog and/or digital circuitryconfigured to perform any of the functions of determining module 1710and/or processor 1420 described above. The functions of determiningmodule 1710 described above may, in certain embodiments, be performed inone or more distinct modules.

Communication module 1720 may perform the transmission functions ofwireless device 110. Communication module 1720 may transmit messages toone or more of network nodes 115 of network 100. Communication module1720 may include a transmitter and/or a transceiver, such as transceiver1410 described above in relation to FIG. 14. Communication module 1720may include circuitry configured to wirelessly transmit messages and/orsignals. In particular embodiments, communication module 1720 mayreceive messages and/or signals for transmission from determining module1710. In certain embodiments, the functions of communication module 1720described above may be performed in one or more distinct modules.

Receiving module 1730 may perform the receiving functions of wirelessdevice 110. Receiving module 1730 may include a receiver and/or atransceiver, such as transceiver 1410 described above in relation toFIG. 14. Receiving module 1730 may include circuitry configured towirelessly receive messages and/or signals. In particular embodiments,receiving module 1730 may communicate received messages and/or signalsto determining module 1710.

Input module 1740 may receive user input intended for wireless device110. For example, the input module may receive key presses, buttonpresses, touches, swipes, audio signals, video signals, and/or any otherappropriate signals. The input module may include one or more keys,buttons, levers, switches, touchscreens, microphones, and/or cameras.The input module may communicate received signals to determining module1710.

Display module 1750 may present signals on a display of wireless device110. Display module 1750 may include the display and/or any appropriatecircuitry and hardware configured to present signals on the display.Display module 1750 may receive signals to present on the display fromdetermining module 1710.

Determining module 1710, communication module 1720, receiving module1730, input module 1740, and display module 1750 may include anysuitable configuration of hardware and/or software. Wireless device 110may include additional modules beyond those shown in FIG. 17 that may beresponsible for providing any suitable functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the various solutionsdescribed herein).

FIG. 18 is a block schematic of an exemplary network node 115, inaccordance with certain embodiments. Network node 115 may include one ormore modules. For example, network node 115 may include determiningmodule 1810, communication module 1820, receiving module 1830, and anyother suitable modules. In some embodiments, one or more of determiningmodule 1810, communication module 1820, receiving module 1830, or anyother suitable module may be implemented using one or more processors,such as processor 1520 described above in relation to FIG. 15. Incertain embodiments, the functions of two or more of the various modulesmay be combined into a single module. Network node 115 may perform theenergy-harvesting routing methods described above with respect to FIGS.1-13.

Determining module 1810 may perform the processing functions of networknode 115. For example, determining module 1810 may determine a firstroute from a first source node to a destination, the first routecomprising one or more relay nodes. As another example, determiningmodule 1810 may determine an energy-harvesting routing metric, theenergy-harvesting routing metric for use in determining a second routefrom a second source node to the destination. As still another example,determining module 1810 may determine the second route from the secondsource node to the destination, the determined second route comprisingone or more relay nodes selected to maximize the determinedenergy-harvesting routing metric.

In some cases, determining module 1810 may determine the second routefrom the second source node to the destination by: determining one ormore first candidate relay nodes, the first candidate relay nodeslocated within a communication range of the second source node;determining which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first source node, the secondsource node, and a first relay node of the first route; and selecting afirst candidate relay node that maximizes the energy-harvesting routingmetric as the first relay node of the second route.

As yet another example, determining module 1810 may: determine one ormore second candidate relay nodes, the second candidate relay nodeslocated within a communication range of the selected first relay node ofthe second route; determine which of the one or more second candidaterelay nodes maximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more second candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first relay node of the firstroute, the first relay node of the second route, and a second relay nodeof the first route; and select a second candidate relay node thatmaximizes the energy-harvesting routing metric as the second relay nodeof the second route.

As another example, determining module 1810 may optimize the determinedfirst route based on the determined second route, the second routecomprising one or more relay nodes selected according to the determinedenergy-harvesting routing metric, wherein the optimized first routemaximizes the energy-harvesting routing metric. In some cases,determining module 1810 may optimize the determined first route based onthe determined second route by determining one or more third candidaterelay nodes, the third candidate relay nodes located within acommunication range of the first source node; determining which of theone or more third candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric is based on the energy-harvesting routing metric of the firstsource node, the second source node, and a first relay node of thesecond route; and selecting a third candidate relay node that maximizesthe energy-harvesting routing metric as a new first relay node of thefirst route.

As another example, determining module 1810 may: determine one or morefourth candidate relay nodes, the fourth candidate relay nodes locatedwithin a communication range of the new first relay node of the firstroute; determine which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more fourth candidate relay nodesmaximizes the energy-harvesting routing metric is based on theenergy-harvesting routing metric of the new first relay node of thefirst route, the first relay node of the second route, and the secondrelay node of the second route; and select a fourth candidate relay nodethat maximizes the energy-harvesting routing metric as a new secondrelay node of the first route.

As still another example, determining module 1810 may optimize thedetermined second route based on the optimized first route, wherein theoptimized second route maximizes the energy-harvesting routing metric.As another example, determining module 1810 may continue to optimize thedetermined first and second routes until the energy-harvesting routingmetric for both the first and second routes exceeds a threshold value.

As yet another example, determining module 1810 may: define a pluralityof subnetworks, the defined plurality of subnetworks comprising at leasta first subnetwork comprising the destination and the first and secondsource nodes and a second subnetwork comprising a second destination anda plurality of source nodes associated with the second destination, theplurality of source nodes including at least one additional source node;determine a first route for the second subnetwork from one of theplurality of source nodes associated with the second destination to thesecond destination, the first route for the second subnetwork comprisingone or more relay nodes; determine a second route for the secondsubnetwork from another of the plurality of source nodes associated withthe second destination to the second destination, the determined secondroute for the second subnetwork comprising one or more relay nodesselected to maximize the determined energy-harvesting routing metric;and optimize the determined first route for the second subnetwork basedon the determined second route for the second subnetwork, the secondroute for the second subnetwork comprising one or more relay nodesselected according to the determined energy-harvesting routing metric,wherein the optimized first route for the second subnetwork maximizesthe energy-harvesting routing metric.

Determining module 1810 may include or be included in one or moreprocessors, such as processor 1520 described above in relation to FIG.15. Determining module 1810 may include analog and/or digital circuitryconfigured to perform any of the functions of determining module 1810and/or processor 1520 described above. The functions of determiningmodule 1810 may, in certain embodiments, be performed in one or moredistinct modules.

Communication module 1820 may perform the transmission functions ofnetwork node 115. Communication module 1820 may transmit messages to oneor more of wireless devices 110. Communication module 1820 may include atransmitter and/or a transceiver, such as transceiver 1510 describedabove in relation to FIG. 15. Communication module 1820 may includecircuitry configured to wirelessly transmit messages and/or signals. Inparticular embodiments, communication module 1820 may receive messagesand/or signals for transmission from determining module 1810 or anyother module.

Receiving module 1830 may perform the receiving functions of networknode 115. Receiving module 1830 may receive any suitable informationfrom a wireless device. Receiving module 1830 may include a receiverand/or a transceiver, such as transceiver 1510 described above inrelation to FIG. 15. Receiving module 1830 may include circuitryconfigured to wirelessly receive messages and/or signals. In particularembodiments, receiving module 1830 may communicate received messagesand/or signals to determining module 1810 or any other suitable module.

Determining module 1810, communication module 1820, and receiving module1830 may include any suitable configuration of hardware and/or software.Network node 115 may include additional modules beyond those shown inFIG. 18 that may be responsible for providing any suitablefunctionality, including any of the functionality described above and/orany additional functionality (including any functionality necessary tosupport the various solutions described herein).

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of thedisclosure. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic. As used in this document, “each” refers to each member of a setor each member of a subset of a set.

Modifications, additions, or omissions may be made to the methodsdescribed herein without departing from the scope of the disclosure. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. Accordingly, the above descriptionof the embodiments does not constrain this disclosure. Other changes,substitutions, and alterations are possible without departing from thespirit and scope of this disclosure, as defined by the following claims.

Abbreviations used in the preceding description include:

-   -   AgN Aggregation Node    -   AP Access Point    -   BS Base Station    -   BSC Base Station Controller    -   BTS Base Transceiver Station    -   CF Compress-and-Forward    -   CPE Customer Premises Equipment    -   D2D Device-to-Device    -   DAS Distributed Antenna System    -   DF Decode-and-Forward    -   eNB eNodeB    -   LAN Local Area Network    -   LME Laptop Mounted Equipment    -   LTE Long Term Evolution    -   M2M Machine-to-Machine    -   MAN Metropolitan Area Network    -   MCE Multi-cell/multicast Coordination Entity    -   MIMO Multiple Input Multiple Output    -   MSR Multi-standard Radio    -   MTC Machine Type Communication    -   NNC Noisy Network Coding    -   PSTN Public Switched Telephone Network    -   QMF Quantize-Map-Forward    -   RAT Radio Access Technology    -   RNC Radio Network Controller    -   RRU Remote Radio Unit    -   RRH Remote Radio Head    -   SF Store-and-Forward    -   SNNC Short Message NNC    -   SNR Signal to Noise Ratio    -   UE User Equipment    -   WAN Wide Area Network    -   WLAN Wireless Local Area Network

The invention claimed is:
 1. A method in a node, comprising: determininga first route from a first source node to a destination, the first routecomprising one or more relay nodes; determining an energy-harvestingrouting metric, the energy-harvesting routing metric for use indetermining a second route from a second source node to the destination;determining the second route from the second source node to thedestination, the determined second route comprising one or more relaynodes selected to maximize the determined energy-harvesting routingmetric; transmitting at least a portion of the second route to one ormore of the second source node and the one or more relay nodes for useby the second source node to transmit data to the destination; andwherein determining the second route from the second source node to thedestination comprises: determining one or more first candidate relaynodes, the first candidate relay nodes located within a communicationrange of the second source node; determining which of the one or morefirst candidate relay nodes maximizes the energy-harvesting routingmetric, wherein the determination of which of the one or more firstcandidate relay nodes maximizes the energy-harvesting routing metric isbased on an energy-harvesting routing metric of the first source node,the second source node, and a first relay node of the first route; andselecting a first candidate relay node that maximizes theenergy-harvesting routing metric as the first relay node of the secondroute.
 2. The method of claim 1, wherein the determined first routecomprises a route having a shortest number of hops between the firstsource node and the destination.
 3. The method of claim 1, comprising:determining one or more second candidate relay nodes, the secondcandidate relay nodes located within a communication range of theselected first relay node of the second route; determining which of theone or more second candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or moresecond candidate relay nodes maximizes the energy-harvesting routingmetric is based on an energy-harvesting routing metric of the firstrelay node of the first route, the first relay node of the second route,and a second relay node of the first route; and selecting a secondcandidate relay node that maximizes the energy-harvesting routing metricas the second relay node of the second route.
 4. The method of claim 1,comprising: optimizing the determined first route based on thedetermined second route, the second route comprising one or more relaynodes selected according to the determined energy-harvesting routingmetric, wherein the optimized first route maximizes theenergy-harvesting routing metric.
 5. The method of claim 4, whereinoptimizing the determined first route based on the determined secondroute comprises: determining one or more third candidate relay nodes,the third candidate relay nodes located within a communication range ofthe first source node; determining which of the one or more thirdcandidate relay nodes maximizes the energy-harvesting routing metric,wherein the determination of which of the one or more third candidaterelay nodes maximizes the energy-harvesting routing metric is based onan energy-harvesting routing metric of the first source node, the secondsource node, and a first relay node of the second route; and selecting athird candidate relay node that maximizes the energy-harvesting routingmetric as a new first relay node of the first route.
 6. The method ofclaim 5, comprising: determining one or more fourth candidate relaynodes, the fourth candidate relay nodes located within a communicationrange of the new first relay node of the first route; determining whichof the one or more fourth candidate relay nodes maximizes theenergy-harvesting routing metric, wherein the determination of which ofthe one or more fourth candidate relay nodes maximizes theenergy-harvesting routing metric is based on an energy-harvestingrouting metric of the new first relay node of the first route, the firstrelay node of the second route, and the second relay node of the secondroute; and selecting a fourth candidate relay node that maximizes theenergy-harvesting routing metric as a new second relay node of the firstroute.
 7. The method of claim 4, comprising: optimizing the determinedsecond route based on the optimized first route, wherein the optimizedsecond route maximizes the energy-harvesting routing metric.
 8. Themethod of claim 7, comprising: continuing to optimize the determinedfirst and second routes until the energy-harvesting routing metric forboth the first and second routes exceeds a threshold value.
 9. Themethod of claim 1, wherein maximizing the energy-harvesting routingmetric comprises maximizing an achievable rate between consecutive relaynodes.
 10. The method of claim 1, wherein the energy-harvesting routingmetric comprises a multiple input multiple output (MIMO) channelcapacity.
 11. The method of claim 1, wherein the energy-harvestingrouting metric is a function of a signal-to-noise ratio.
 12. The methodof claim 1, wherein maximizing the energy-harvesting routing metriccomprises maximizing interference between routes.
 13. The method ofclaim 1, wherein the relay nodes perform noisy network coding.
 14. Themethod of claim 1, comprising: defining a plurality of subnetworks, thedefined plurality of subnetworks comprising at least a first subnetworkcomprising the destination and the first and second source nodes and asecond subnetwork comprising a second destination and a plurality ofsource nodes associated with the second destination, the plurality ofsource nodes including at least one additional source node; determininga first route for the second subnetwork from one of the plurality ofsource nodes associated with the second destination to the seconddestination, the first route for the second subnetwork comprising one ormore relay nodes; determining a second route for the second subnetworkfrom another of the plurality of source nodes associated with the seconddestination to the second destination, the determined second route forthe second subnetwork comprising one or more relay nodes selected tomaximize the determined energy-harvesting routing metric; and optimizingthe determined first route for the second subnetwork based on thedetermined second route for the second subnetwork, the second route forthe second subnetwork comprising one or more relay nodes selectedaccording to the determined energy-harvesting routing metric, whereinthe optimized first route for the second subnetwork maximizes theenergy-harvesting routing metric.
 15. The method of claim 14, whereinthe first route for the second subnetwork is determined usinginterference-aware routing.
 16. The method of claim 1, wherein the firstroute and the second route comprise different numbers of relay nodes.17. A node, comprising: one or more processors, the one or moreprocessors configured to: determine a first route from a first sourcenode to a destination, the first route comprising one or more relaynodes; determine an energy-harvesting routing metric, theenergy-harvesting routing metric for use in determining a second routefrom a second source node to the destination; determine the second routefrom the second source node to the destination, the determined secondroute comprising one or more relay nodes selected to maximize thedetermined energy-harvesting routing metric; transmit at least a portionof the second route to one or more of the second source node and the oneor more relay nodes for use by the second source node to transmit datato the destination; and wherein the one or more processors configured todetermine the second route from the second source node to thedestination comprise one or more processors configured to: determine oneor more first candidate relay nodes, the first candidate relay nodeslocated within a communication range of the second source node;determine which of the one or more first candidate relay nodes maximizesthe energy-harvesting routing metric, wherein the determination of whichof the one or more first candidate relay nodes maximizes theenergy-harvesting routing metric is based on an energy-harvestingrouting metric of the first source node, the second source node, and afirst relay node of the first route; and select a first candidate relaynode that maximizes the energy-harvesting routing metric as the firstrelay node of the second route.
 18. The node of claim 17, wherein thedetermined first route comprises a route having a shortest number ofhops between the first source node and the destination.
 19. The node ofclaim 17, wherein the one or more processors are further configured to:determine one or more second candidate relay nodes, the second candidaterelay nodes located within a communication range of the selected firstrelay node of the second route; determine which of the one or moresecond candidate relay nodes maximizes the energy-harvesting routingmetric, wherein the determination of which of the one or more secondcandidate relay nodes maximizes the energy-harvesting routing metric isbased on an energy-harvesting routing metric of the first relay node ofthe first route, the first relay node of the second route, and a secondrelay node of the first route; and select a second candidate relay nodethat maximizes the energy-harvesting routing metric as the second relaynode of the second route.
 20. The node of claim 17, wherein the one ormore processors are further configured to: optimize the determined firstroute based on the determined second route, the second route comprisingone or more relay nodes selected according to the determinedenergy-harvesting routing metric, wherein the optimized first routemaximizes the energy-harvesting routing metric.
 21. The node of claim20, wherein the one or more processors configured to optimize thedetermined first route based on the determined second route comprise oneor more processors configured to: determine one or more third candidaterelay nodes, the third candidate relay nodes located within acommunication range of the first source node; determine which of the oneor more third candidate relay nodes maximizes the energy-harvestingrouting metric, wherein the determination of which of the one or morethird candidate relay nodes maximizes the energy-harvesting routingmetric is based on an energy-harvesting routing metric of the firstsource node, the second source node, and a first relay node of thesecond route; and select a third candidate relay node that maximizes theenergy-harvesting routing metric as a new first relay node of the firstroute.
 22. The node of claim 21, wherein the one or more processors arefurther configured to: determine one or more fourth candidate relaynodes, the fourth candidate relay nodes located within a communicationrange of the new first relay node of the first route; determine which ofthe one or more fourth candidate relay nodes maximizes theenergy-harvesting routing metric, wherein the determination of which ofthe one or more fourth candidate relay nodes maximizes theenergy-harvesting routing metric is based on an energy-harvestingrouting metric of the new first relay node of the first route, the firstrelay node of the second route, and the second relay node of the secondroute; and select a fourth candidate relay node that maximizes theenergy-harvesting routing metric as a new second relay node of the firstroute.
 23. The node of claim 20, wherein the one or more processors arefurther configured to: optimize the determined second route based on theoptimized first route, wherein the optimized second route maximizes theenergy-harvesting routing metric.
 24. The node of claim 23, wherein theone or more processors are further configured to: continue to optimizethe determined first and second routes until the energy-harvestingrouting metric for both the first and second routes exceeds a thresholdvalue.
 25. The node of claim 17, wherein maximizing theenergy-harvesting routing metric comprises maximizing an achievable ratebetween consecutive relay nodes.
 26. The node of claim 17, wherein theenergy-harvesting routing metric comprises a multiple input multipleoutput (MIMO) channel capacity.
 27. The node of claim 17, wherein theenergy-harvesting routing metric is a function of a signal-to-noiseratio.
 28. The node of claim 17, wherein the one or more processors areconfigured to maximize the energy-harvesting routing metric bymaximizing interference between routes.
 29. The node of claim 17,wherein the relay nodes perform noisy network coding.
 30. The node ofclaim 17, wherein the one or more processors are further configured to:define a plurality of subnetworks, the defined plurality of subnetworkscomprising at least a first subnetwork comprising the destination andthe first and second source nodes and a second subnetwork comprising asecond destination and a plurality of source nodes associated with thesecond destination, the plurality of source nodes including at least oneadditional source node; determine a first route for the secondsubnetwork from one of the plurality of source nodes associated with thesecond destination to the second destination, the first route for thesecond subnetwork comprising one or more relay nodes; determine a secondroute for the second subnetwork from another of the plurality of sourcenodes associated with the second destination to the second destination,the determined second route for the second subnetwork comprising one ormore relay nodes selected to maximize the determined energy-harvestingrouting metric; and optimize the determined first route for the secondsubnetwork based on the determined second route for the secondsubnetwork, the second route for the second subnetwork comprising one ormore relay nodes selected according to the determined energy-harvestingrouting metric, wherein the optimized first route for the secondsubnetwork maximizes the energy-harvesting routing metric.
 31. The nodeof claim 30, wherein the first route for the second subnetwork isdetermined using interference-aware routing.
 32. The node of claim 17,wherein the first route and the second route comprise different numbersof relay nodes.
 33. A computer program product comprising instructionsstored on non-transient computer-readable media which, when executed byone or more processors, perform the acts of: determining a first routefrom a first source node to a destination, the first route comprisingone or more relay nodes; determining an energy-harvesting routingmetric, the energy-harvesting routing metric for use in determining asecond route from a second source node to the destination; determiningthe second route from the second source node to the destination, thedetermined second route comprising one or more relay nodes selected tomaximize the determined energy-harvesting routing metric; transmittingat least a portion of the second route to one or more of the secondsource node and the one or more relay nodes for use by the second sourcenode to transmit data to the destination; and wherein determining thesecond route from the second source node to the destination comprises:determining one or more first candidate relay nodes, the first candidaterelay nodes located within a communication range of the second sourcenode; determining which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric, wherein thedetermination of which of the one or more first candidate relay nodesmaximizes the energy-harvesting routing metric is based onenergy-harvesting routing metrics of the first source node, the secondsource node, and a first relay node of the first route; and selecting afirst candidate relay node that maximizes the energy-harvesting routingmetric as the first relay node of the second route.